The overall objective of this project is to learn as much as possible about the life cycle and assembly of filamentous bacteriophage. It is our belief that the information obtained on this class of virus will help in understanding the morphogenesis and mode of action of some types of mammalian viruses that release viral progeny without causing cell lysis. In addition to the major coat (B) protein and the minor adsorption (A) protein, we have identified two other minor coat proteins (the C and D proteins) of bacteriophage fd as being phage specific and products of genes 9 and 6. We are in the process of locating their position in the virus and of trying to determine their role in phage infection. We have developed a biological assay for the A protein (a product of gene 3) and we are using it to locate the domains of the A protein which are responsible for various functions displayed by the A protein. We intend to make use of cloning techniques to produce reasonable quantities of several of the phage-coded proteins of unknown function to test for their role and locating during the infective process. This will be attempted by preparing specific antisera, by examining and reconstructing partial reactions that occur during phage assembly. We also plan to examine several well defined intracellular viral DNA intermediates for the presence of specific phage and host derived proteins that play a part in phage replication and assembly. Finally a study will be made of the host proteins that affect virus assembly.